In the past, optical correlators have been made with discrete components which required many adjustments to align the optical train. After normal elements such as mirrors and lenses are aligned, the critical remaining issue unique to optical correlators is to adjust the Holographic Fourier Transform Matched Filter to the exact optical axis (zero spatial frequency Fourier Transform) of the laser beam. This unique alignment must be done to the order of a few micrometers. This is usually done in laboratory style correlators by having the matched filter placed in a microscopically adjustable holder.
Recently, an optical correlator based on a single block of glass has been fabricated in order to make it rugged. No alignment of the optical components is needed or possible yet the matched filter must still be aligned. This is difficult since it is inside the optical system. It is even more difficult to insert a mechanism for switching between multiple filters which is a desired function of matched filters.
Building a correlator utilizing a laser diode as the light source has complications in that the active emitting location on the diode is not accurately registered to the outside of the laser diode package.
Therefore, it is an object of this invention to provide a way for aligning each laser diode relative to the correlator structure and the matched filter of the correlator.
Another object of this invention is to provide a simple procedure in which a laser diode can be accurately mounted relative to a matched filter of a correlator.
Other objects and advantages of this invention will be obvious to those skilled in this art.